Saharan dust becomes more life-sustaining as it travels across the Atlantic Ocean

Iron, a crucial micronutrient for life, enables vital processes such as photosynthesis and DNA synthesis.

In Short

• Iron availability often limits biological productivity.
• The longer Saharan dust travels, the more bioreactive its iron content becomes
• The research team analysed drill cores from the Atlantic Ocean floor

A new study published in Frontiers in Marine Science reveals that iron-rich dust from the Sahara Desert becomes more biologically available to marine organisms as it travels across the Atlantic Ocean.

This discovery has significant implications for understanding global climate patterns and oceanic ecosystems.

Iron, a crucial micronutrient for life, enables vital processes such as photosynthesis and DNA synthesis.

In many parts of the world's oceans, iron availability often limits biological productivity. The new research, led by Dr. Jeremy Owens from Florida State University, demonstrates that the longer Saharan dust travels, the more bioreactive its iron content becomes.

"We show that iron bound to dust from the Sahara blown westward over the Atlantic has properties that change with the distance traveled: the greater this distance, the more bioreactive the iron," explained Dr. Owens.

This relationship suggests that atmospheric chemical processes convert less accessible forms of iron into more biologically available ones during transport.

The research team analysed drill cores from the Atlantic Ocean floor, collected by the International Ocean Discovery Program. They focused on four cores at varying distances from the Sahara-Sahel Dust Corridor, examining sediments deposited over the last 120,000 years.

Using advanced techniques, including plasma-mass spectrometry, the scientists measured total iron concentrations and isotope compositions consistent with Saharan dust. They also determined the proportions of different iron minerals in the sediments.

Crucially, the study found that the proportion of bioreactive iron was lower in cores farther from the dust source. This indicates that more bioreactive iron had been consumed by marine organisms before reaching the ocean floor in distant locations.

Dr. Timothy Lyons, a co-author from the University of California at Riverside, emphasised the significance of these findings: "Dust that reaches regions like the Amazonian basin and the Bahamas may contain iron that is particularly soluble and available to life, thanks to the great distance from North Africa, and thus a longer exposure to atmospheric chemical processes."

This research provides valuable insights into how atmospheric iron transport influences marine ecosystems and potentially impacts global climate patterns.

By enhancing our understanding of nutrient cycles in the ocean, this study could have far-reaching implications for climate modeling and marine conservation efforts.